The present invention generally relates to a network system such as Internet through which individually managed and operated networks are interconnected, and particularly to a network structure method for increasing the speed of the routing that determines what route is used to transmit communication information of packets with destination address added, and to a router for use in this method.
The transmission of communication information through Internet or the like in which individually managed and operated networks are mutually connected is not performed as in the telephone network in which the operation and management of networks are centralized to connect the information transmitting person and the receiving person and to transmit information therebetween. An address capable of unique identification on network is assigned to each computer site or machine, and a packet with the destination address is transmitted to the opponent. In this case, the route determination equipment connected in networks, called as router, is used to control the routing. The router within each network has a routing table on which address information of its own network and neighbor networks are registered, and refers to this table, thus routing to determine the necessary route.
The conventional routing control in this Internet or the like can be divided into two routing controls: routing control between networks each of which is operated on the same management power called autonomous system (abbreviated AS) and routing control within an AS. For example, when a network constructed by connecting a plurality of LANs present within one corporation through a router is managed and operated by the company-wide department, this network corresponds to AS. Routing information exchange within an AS is performed by routing protocol called IGP (Internal Gateway Protocol), and routing information exchange between ASs by routing protocol called EGP (External Gateway Protocol). A router for the connection and route control between adjacent ASs is called border router. The border router produces a list of routes (routing table) from the routing information obtained by IGP and EGP. When, an address for new equipment is added within the own AS, the routing table of the border router is changed according to the addition by use of IGP, and the change is transmitted to border routers of other ASs by use of EGP.
Recently, the Internet has been complicated as a result of interconnection of a large number of networks. On the other hand, the route determination equipment such as border router has a limit to the amount of address to be stored because the routing information acquisition and routing process speed are restricted. Therefore, the present route determination equipment cannot hold all the address information in the Internet, but can hold only the address information chiefly of networks physically and logically near to the own network (AS). If the amount of address that the route determination equipment holds is less than all the address in the Internet, packets with destination not specified increase, resulting in performance deterioration of all networks. Thus, it is necessary not to increase the amount of routing information that each route determination equipment holds, and not to deteriorate the performance of networks.
In addition, the present information processor often works with other information processors connected to networks to treat information. Therefore, it is important to consider the situations of the networks and the load on the information processor of the linked opponent, and it is necessary to swiftly make route determination.
It is an object of the invention to enable fast routing to be made in Internet or the like in which a plurality of individually managed and operated autonomous systems are interconnected, and information processors on networks to smoothly communicate with each other.
According to the invention, the autonomous systems that constitute the network system are divided into groups, and routing information is taken around between the route determination equipment (border routers) of the autonomous systems of each group, or the routers of the same group share common routing information. The route determination equipment has means for separating a desired autonomous system of the corresponding group or consolidating autonomous systems of other groups into its own group in accordance with the input/output traffic to or from the corresponding group, thereby making it possible to hold routing information necessary for the processing ability within the group.